Association Between Obesity-related Anthropometric Indicators And Colorectal Neoplasms

Background and objectives Overweight and obesity are abnormal or excessive fat accumulation in the body.In 2016,the overweight rate of Chinese adults was 32.3%,and the obesity rate was 6.2%.Overweight and obesity are risk factors for many chronic diseases,such as cancer.Colorectal neoplasms include colorectal cancer,colorectal adenoma,and colorectal polyp.Colorectal cancer is a common malignant tumor of the digestive tract.In 2018,the incidence of colorectal cancer in China was 36.6/100,000,and the mortality rate was 17.4/100,000,causing a huge burden of disease.Colorectal adenoma and polyp are considered as precancerous lesions of colorectal cancer.Early detection and intervention can effectively reduce the incidence and mortality of colorectal cancer.Obesity may be closely associated to all stages of colorectal cancer,but the association varies with factors such as race,sex,type of lesion,and location of the lesion.Most of the current studies are based on foreign populations.There is no research reporting whether the effects of obesity on the various stages of colorectal cancer are different on Chinese populations.Therefore,we conducted a cross-sectional study of people at high risk for colorectal cancer and explored the association between obesityrelated anthropometric indicators(BMI,waist circumference,waist-hip ratio,and waistheight ratio)and colorectal cancer,colorectal adenoma,and colorectal polyp.The aim is to reveal the association between obesity and various stages of colorectal cancer,providing a theoretical basis for the prevention of colorectal cancer.Material and methods This study relied on Jiashan County's colorectal cancer early diagnosis and early treatment screening project,and performed anthropometric measurements,questionnaire surveys,and colonoscopy in high-risk populations of colorectal cancer who were initially screened from August 2012 to December 2018.According to the results of colonoscopy,14293 normal controls,156 colorectal cancer cases,5005 colorectal adenoma cases,and 1026 colorectal polyp cases were included.BMI is divided into four categories: <18.5kg/m2 is underweight,18.5-23.9kg/m2 is normal weight,24.0-27.9kg/m2 is overweight,and ? 28.0kg/m2 is obese.Waist circumference,waist-hip ratio,and waist-height ratio are all divided into two categories: waist circumference?90cm for men or ?85cm for women is abdominal obesity;waisthip ratio?0.90 for men or ?0.85 for women is abdominal obesity;waist-height ratio?0.5 is abdominal obesity.An unconditional logistic regression model was used to calculate the odds ratio(OR)and its 95% confidence interval(CI).Covariates included sex,age,individual cancer history,family history for colorectal cancer,smoking,drinking,physical exercise and aspirin use.Colorectal neoplasms were classified according to the type and location of the lesion,and subgroup analysis was performed.Statistical analysis was performed using R software version 3.5.3.The significance level was bilateral ? = 0.05,and P <0.05 was considered statistically significant.Results Excessive waist circumference was associated with an increased risk of colorectal cancer.After adjusting for covariates,subjects with excessive waist circumference had a 1.98(95%CI 1.43-2.73)times higher risk of colorectal cancer and had 2.28(95% CI 1.57-3.33)times higher risk of distal colon or rectal cancer,compared with those with normal waist circumference.Excessive BMI,waist circumference,waist-hip ratio,and waist-height ratio were all associated with an increased risk of colorectal adenoma.After adjusting for covariates,the risk of colorectal adenomas in the BMI 24.0-27.9 and BMI?28 groups were 1.10(95%CI 1.03-1.19)and 1.40(95%CI 1.24-1.59)times higher than that in normal BMI group,respectively.The risk of colorectal adenoma in those with excessive waist circumference,waist-hip ratio and waist-height ratio were 1.27(95%CI 1.19-1.36),1.40(95%CI 1.26-1.55),1.18(95%CI 1.10-1.27)times higher than that in normal subjects.Subgroup analysis showed that BMI,waist circumference,waist-hip ratio and waistheight ratio were more closely associated with proximal colon adenoma.Excessive BMI,waist circumference,waist-hip ratio,and waist-height ratio were all associated with an increased risk of colorectal polyp.After adjusting for covariates,the risk of colorectal polyp was 1.45(95% CI 1.26-1.66)and 1.67(95% CI 1.31-2.10)in the BMI 24.0-27.9 and BMI ? 28.0 groups,respectively.Those with excessive waist circumference,waist-hip ratio and waist-height ratio were 1.53(95% CI1.35-1.74),1.43(95% CI 1.17-1.76),and 1.43(95% CI 1.23-1.66)times more likely to having colorectal polyp.Subgroup analysis showed that BMI,waist circumference,waist-hip ratio,and waist-height ratio were only associated with the risk of hyperplastic polyp,but not with inflammatory polyp.Conclusions Excessive BMI,waist circumference,waist-hip ratio,and waist-height ratio are associated with an increased risk of colorectal neoplasms in populations at high risk for colorectal cancer.Excessive waist circumference is associated with the risk of colorectal cancer,especially with the distal rectal cancer;four excessive indicators are associated with an increased risk of colorectal adenoma,especially with proximal colon adenoma;four excessive indicators are associated with an increased risk of colorectal polyp,especially with hyperplastic polyp.Of the four obesity-related anthropometric indicators,excessive waist circumference alone is associated with an increased risk of colorectal cancer,colorectal adenoma,and colorectal polyp.This study suggests that abdominal obesity,as measured by waist circumference,may play a role in the development of colorectal cancer.Therefore,waist circumference control should be used as a preventive strategy for colorectal cancer.